Sign sensing switch for numerical control system



Feb. 18 1969 A- R. LUDWIG SIGN SENSING SWITCH FOR NUMERICAL CONTROLSYSTEM Filed June 7, 1966 Sheet T a m W M 1 e m 7 m p, M W A M w M M i H4 a w a m 7 3 2 53 2 4 c Z i 2 M 4 Z 2 w 2 2 L\7 7 K MK ,w SW fl fif J 37 4 4 J Z a m 2 g 4 a A. R. LUDWIG Feb. 18, 1969 Sheet Filed June 7.1966 LT k a Q K e w w 2 E W /u. 7/ im 6 B 4 WW xm 2 k: 2 7 5 A m a 5 TLl P L Q\ M 6 1||||| T m w a Z I a I Z1 a f. r u n 3 u l 8 u I n 5/ F:II IL r 1L 1 v w a m 5 M z z 6 INVENTOR.

14165? (MOM/G United States Patent 0.]

3,428,765 SIGN SENSING SWITCH FOR NUMERICAL CONTROL SYSTEM Albert R.Ludwig, Timberlake, Ohio, assignor to Zagar, Inc., Cleveland, Ohio, acorporation of Ohio Filed June 7, 1966, Ser. No. 555,782

US. Cl. 200-6139 Claims Int. Cl. H01h 3/10 ABSTRACT OF THE DISCLOSURE Anelectrical switch which is responsive to the direction in which theswitch is turned, comprising a housing, a shaft rotatable in thehousing, a cam carried by the shaft and having a cam follower engaged bythe cam for operating first and second switches through firstand secondswitch actuating means. If the shaft is rotated in a first direction,the first switch is operated and, similarly, if the shaft is rotated ina second direction, the second switch is operated.

This invention relates generally to electrical switching circuits andmore particularly to sign or directional sensing switches particularlyadapted for use in input registers of numerical control systems.

There are many applications, particularly in the case of rotary switchesof the multiple position type, where it is desired to provide a sensingmeans or signal to indicate the direction in which the switch is turned.For example, certain numerical control systems such as that disclosed inmy co-pending application, Scr. No. 532,029, filed Jan. 17, 1966, nowUS. Patent No. 3,346,183, issued Oct. 10, 1967, have a position input inthe form of an input register in which the count is determined by thesetting of a plurality of rotary switches. To avoid an unnecessaryseries of operations it is desirable to have a sign or direction inputsignal to indicate whether the new setting .in a register is higher orlower in numerical value than the existing setting. While this can bedone by a separate input, chances of error are reduced and speed ofopera- .tion increased by the present invention which provides for anautomatic signal of sign or direction when the new position is set inthe input register.

The foregoing is accomplished by the provision of a novel switchingarrangement which is combined with each of the rotary switches so as toclose different sets of con tacts depending upon the direction ofrotation of the switch shaft. Thus, if the shaft is turnedcounter-clockwise one circuit is closed upon each step of switchrotation and if the switch is turned clockwise, a different switchingcircuit is closed. These circuits may be arranged to actuate relays toproduce a sign or direction sensing signal and may be arranged with eachof the switches so that if the switches are set in numerical orderstarting with the highest digit to be changed, a correct sign input willbe produced concurrently with the new position input.

The switching unit for providing this feature includes astar wheelmember which is rotatable with the switch shaft and is mounted within ahousing having a ball in engagement with the star wheel. The sides ofthe notches in the star wheel may be at approximately 90' degree anglesand at similar angles may be a pair of springloaded plungers which mayrest in contact with the ball. In any case, the arrangement is such thatrotation of the star wheel in one direction or the other establishes adriving relationship between the ball, as the driving member, and one ofthe plungers so as to actuate a switch by movement of that plunger.Thus, each step-wise rotation of the switch shaft produces a momentaryclosing of the switch contacts to indicate the direction of rotation ofthe switch shaft. The switch may be utilized in a circuit m 3,428,765Patented Feb. 18, 1969 which is responsive only to the first impulse,that is the first closing of one or the other contacts by rotation ofone of the switches, so that the sign sensing circuit is thereafterdeactivated and subsequent numerical changes do not affect the system.

The switch in its construction has a simplicity which lends itself tolow cost of manufacture while maintaining a high degree of reliabilityand is particularly arranged so as to be adaptable for addition toexisting rotary switches with a minimum of alteration. Further objectsand advantages of this invention will readily become apparent to thoseskilled in the art upon a more complete understanding of the inventionas disclosed in the drawings and the following detailed description.

In the drawings:

FIG. 1 is a side-elevational view of a rotary switch incorporating theswitching mechanism according to the preferred embodiment of the presentinvention;

FIG. 2 is a rear-elevational view of the switch shown in FIG. 1;

FIG. 3 is an enlarged cross-sectional view through the direction sensingswitch taken on line 33 of FIG. 1; and

FIG. 4 is a schematic view of an input register circuit incorporatingthe switch of FIGS. 1-3.

Referring now to the drawings in greater detail, the switch unit shownin FIGS. 13 includes an ordinary rotary selector switch which may be ofthe ten or twelve position wafer type, and to which the directionsensing switch has been added. This rotary switch may be of any usualtype well known in the art and commercially available and includes ahousing 10 having a projecting threaded boss 11 by which the switch isattached to a control panel. A rotary shaft 12 extends axially throughthe housing 10 in which it is journalled by suitable bearing means. Aselector switch unit 14 provides the multiple position switches within ahousing and to which electrical connection may be made by means of theradially extending lugs 15. A pair of studs 16 extend between thehousing 10 and the switch unit 14 and secure the assembly together bymeans of nuts 17. Since the structure of this switch is well known inthe art and forms no part of the present invention except to the extentdescribed hereinafter, it will not be described in further detail.

The housing 20 carries the direction sensing switch mechanism and ismounted on the studs 16 between the housing 10 and selector switch unit14. This mounting is merely an arrangement for convenience to allowaccess to the lugs 15 for soldering purposes, and it is understood thatthe housing 20 of the direction sensing switch mechanism can be suitablyactuated by any extension of the shaft 12 on either end of the switch.The housing 20 is preferably made of an insulating material and may beof uniform thickness as shown most clearly in FIG. 1. If desired forinsulating purposes, insulating plates or covers may be placed on thefront and back sides of the housing 20 to insulate it from the housing10* or selector switch units 14.

The housing 20 has a circular opening 22 extending therethrough aboutthe axis of shaft 12. A rotary cam member or star Wheel 24 is mountedwithin the opening 22 and secured to the shaft 12 by suitable means suchas a press fit or a key to rotate therewith. The star wheel 24 has aplurality of cam surfaces in the form of notches 26 around its outerperiphery. Preferably, these notches 26 have sides forming an includedangle of about degrees and are equal in number and spacing to the rotarypositions of the switch. In the case of a ten position switch there maybe ten of the notches 26, or as shown as applied to a twelve positionswitch with two positions unused, there are twelve notches. The notchesmust have an angular spacing corresponding to the angular switchpositions to insure that the normal detent mechanism of the switch forholding the shaft in a given position also allows appropriate alignmentof the notches 26.

The housing has a pair of left and right bores 28 and 29 extendingradially therein with their axes substantially normal to the notch sideswhen the notch is centered at the intersection of the axes of the bores28 and 29. It will be noted that these bores are located so that attheir inner ends the sides are substantially in line with the adjacentnotch side. The bores have a diameter at least as great as that of theball 35 which is located within the notch 26 so that rotation of thestar wheel will cause the notch sides to engage the ball and force itinto the appropriate one of the bores. Plungers 30 and 31 are mountedwithin the bores 28 and 29 for a free-sliding fit and may be providedwith steps indicated in 32 and 33 to limit inward movement of plungerstoward the ball 35. It will be seen with this arrangement that when thenotch is centered, both of the plungers rest at the inner ends of theirbores with the steps 32 and 33 in abutment against the housing andsubstantially in contact with the ball 35 when it is also in contactwith the sides of the notch 26. Any rotation of the star wheel 24 willforce the ball outwardly in a direction normal to the notch sideengaging the ball. Thus, rotation of the star wheel in acounterclockwise direction will shift the ball 35 against the plunger 30and clockwise rotation will shift the ball against the right plunger 31.It will be understood that the plungers 30 and 31 arespring biasedinwardly as explained hereinafter, and the ball will be forced up toshift the plunger outward a sufficient distance until the ball is ableto roll over the point 27 between adjacent notches and then passdownward into the next notch and allow the plunger to return to thenormal position.

The switching mechanism and arrangement for biasing the plungers 30 and31 is mounted on the upper end of the housing on an integral projection36. Inner leaf springs 38 and 39 are secured adjacent to the sides ofthe projection 36 and extend downward to rest against the sloping sides37 of the housing 20 adjacent the outer ends of the plungers. Theseleaves 38 and 39 are relatively thin and resilient and serve to bias theplungers toward the inward position while being yieldable upon outwardmovement of the plunger to allow the contacts to close. Outward of theleaves 38 and 39 adjacent the projection 36 are a pair of insulatingspacers 40 and 41, against the outer surfaces of which are mounted outerleaves 42 and 43 which preferably have greater thickness than innerleaves for greater stiffness against deflection. The outer leaves 42 and43 extend substantially parallel to the inner leaves at all points andat their lower ends carry contacts 42a and 43a to make electricalcontact with mating contacts 38a and 39a on the inner leaves when theadjacent plunger deflects the inner leaf outward to move the adjacentcontacts into engagement to allow an electric signal to pass between theadjacent inner and outer leaf.

Outward of the outer leaves 42 and 43 are additional insulating spacers44 and 45 which are clamped by metal plates 46 and 47. Screws 49 passthrough the entire assembly between the outer plates 46 and 47 withwhich they are engaged to clamp the complete assembly on the projections36. The screws 49 are provided with insulating sleeves 50 so as toinsure proper insulation of the leaves. It will be understood that thenecessary electrical connections with the circuit may be made at thefree ends of the leaves projecting beyond the housing projection 36 bysoldering or any other suitable manner,

From the foregoing, it will be seen that the invention provides a switchassembly which may be mounted on a conventional rotary selector switchso that depending upon the direction of rotation of the switch shaft 12,the star wheel 24 will be turned so as to produce momentary closing ofone of the adjacent contacts for each stepwise rotation of the shaft andstar wheel. Since separate sets of contacts close with differentdirections of rotation, a signal is provided by the appropriateswitching contacts to indicate the direction in which the shaft has beenturned.

Turning now to FIG. 4, this circuit shows an application of the switchof FIGS. 13 applied to a four digit position register and arranged toproduce actuation of contact relays upon the initial rotation of one ofthe direction sensing switches and to disconnect that switch and theremaining switches from further action after the initial closing of theswitch contacts.

The circuit has four input register switches indicated at 51, '52, 53and 54 corresponding to a four digital position register. These switcheshave merely been shown by schematic representation only since the actualcircuitry of the register switches is not a part of this invention.Electric current is supplied to the circuit by lines 56 and 57 and astarting circuit is located in line 58 across lines 56 and 57. A startswitch 59 of the momentary contact normally open type is connectedacross normally open contacts 60 actuated by a contact relay in line 58indicated at ICR. In series with the contact relay 1CR are normallyclosed contacts 65 and 66 of contact relays 2CR and 3CR, respectively.Thus, when the starting switch 59 is depressed, the relay 1CR will beactuated to close the contacts 60 to maintain contact relay 1CRenergized unless either of the contacts 65 and 66 are opened. Theactivation of relay ICR also closes contacts 67 and 68 to connect thelines '56 and 57 to provide energization of the rest of the circuit.

Each of the input switches 51-54 has a direction sensing switchassociated therewith actuated by the common shaft and which may beconsidered for switching purposes as a single pole double-throw switch.This action can be attained by connecting together the two inner leaves38 and 39 and these contacts indicated at 61, 62, 63 and 64 areconnected to the line 56. When any of these switches are actuated byrotating the shaft in one direction, as by rotating the shaft todecrease the numerical value in the register, the contacts 61, 62, 63and 64 make contact respectively at 61a, 62a, 63a and 64a to connectthrough line 70 to energize contact relay 2CR which is connected to theother line 57. Likewise, actuation of these switches by rotation in theopposite direction to increase the numerical value will make contact at61b, 62b, 63b and 64b to connect through line 71 to energize contactrelay 3CR which is likewise connected at its other side to the otherline 57. It will be understood that only one of the switches 61-64 willoperate to provide the sign or direction sensing signal and the circuitis arranged so that actuation of one of the switches and the subsequentenergization of either 2CR or 3CR will render the circuit inoperative.This is accomplished by the contacts 65 and 66 in line 58 which openwhen either contact relay 2CR or 3CR is energized so as to de-energizerelay 1CR to cause the opening of contacts 67 and 68 to prevent anyfurther supply from lines 56 and 57 to the switches 61-64.

However, the contact relays 2CR and 3CR are preferably of the time delaytype in which there is a slight delay after actuation before thecontacts are operated so as to allow actuation of the signaling relays.The signaling relays are actuated by having the contacts 61a-64aconnected through a line 72 and normally closed contact 74 of contactrelay 4CR to contact relay 5CR which is energized by completing thecircuit through line 78 which connects to the supply line 57. Likewise,the contacts 61b-64b are connected through line 73 and normally closedcontact 75 of relay 4CR to energize 4CR which is also connected to line78. Upon the energization of either of the contact relays 4CR or SCR,the appropriate one of the normally closed contacts 74 and 75 is opened,but before this is done on the basis of a make-before-break arrangementof the contacts, either of the appropriate contacts 80 and 81 of relaysSCR and 4CR, respectively, are closed to maintain energization of theappropriate one of the relays through line 82 which connects to line 56.

Thus, when the circuit of FIG. 4 is designed to be used for providing asign signal output by means of additional contacts on either of thecontact relays 4CR or SCR, the switch system is actuated by closing ofthe switch 59 to energize relay 1CR in line 58. This allows energizationof the contact relays 2CR and 3CR when the appropriate one of theswitches 61-64 is actuated by changing the setting of the input switches51-54. Upon the movement of any one of these switches, the appropriateone of the switches 61-64 is actuated to close one of its contacts tothereby energize either of the contact relays 4CR or SCR and provide theappropriate sign or direction signal. To prevent any further signalwhich would actuate the other relay, after the short time de-,

lay, either relay 2CR or 3CR operates to open either of the contacts 65or 66 in line 58 so thatrelay 1CR drops out thereby opening the contacts67 and 68. Since one of the relays 4CR or SCR has been energized throughthe lines 78 and 82, the opening of the contacts 67 and 68 does notaffect these relays which will continue to be energized untilde-energized by the completing of the cycle.

Although the invention has been described in detail as to both structureand mode of operation, it is recognized that it is not limited to thestructural details shown and modifications and rearrangements which willreadily become obvious to those skilled in the art upon comprehension ofthis invention remain within the scope of the invention as defined inthe claims.

I claim:

1. A directional responsive electrical switch comprising a housing, ashaft rotatable in said housing, cam means carried by said shaft, camfollower means contacted and operated by said cam means, first andsecond switch actuating means movably supported by said housing and eachselectively contacted and operated by said cam follower means uponrotation of said shaft with the said selection being determined by thedirection of said rotation, and first and second switches contacted andoperated respectively by said first and second actuating means. 4

2. A switch as set forth in claim 1 wherein said cam means is a wheelhaving a plurality of radial notches with sloping sides on itsperiphery.

3. A switch as set forth in claim 2 wherein said actuating means areplungers slidable in said housing along an axis substantially normal toa sloping side of a notch when said cam follower means is interposedbetween the plunger and the sloping side.

4. A directional responsive electrical switch comprising a housing, ashaft rotatable in said housing, a cam wheel carried by said shaft andhaving a plurality of notches, cam follower means movably mounted insaid housing in engagement with said notches for movement to and fromsaid cam wheel, first and second switch actuating means movablysupported by said housing and selectively engaged by said cam followermeans upon movement of said cam follower means out of one of saidnotches, whereby rotation of said shaft in one direction causes said camfollower means to operate said first switch actuating means and rotationof said shaft in the opposite direction causes said cam follower meansto operate said second switch actuating means, and first and secondswitches operable by said first and second switch actuating means.

5. A switch as set forth in claim 4 wherein said first and secondswitches are of the momentary contact type.

6. A switch as setforth in claim 4 wherein said first and second switchactuating means are plungers slidably mounted in said housing, eachalong an axis substantially normal to a sloping side of a notch whensaid cam follower means is interposed between the plunger and thesloping side.

7. A switch as set forth in claim 6 wherein said notches are V-shapedand have an included angle of substantially degrees.

8. A switch as set forth in claim 4 wherein said switches include leafspring contact members which bias said switch actuating means and saidcam follower means into engagement with the notches of said cam wheel.

9. A switch as set forth in claim 4 wherein said cam follower means is aball.

10. A switch as set forth in claim 6 wherein said notches are on theradially outer periphery of said cam wheel, and said plungers aremovable in the plane of said cam wheel.

References Cited UNITED STATES PATENTS 647,291 4/1900 Chapman 200-l532,427,453 9/1947 Hadley 200-61.39 2,767,268 10/1956 Levine ZOO-61.39

ROBERT K. SCHAEFER, Primary Examiner.

M. GINSBURG, Assistant Examiner.

US. Cl. X.R.

